1. Field of the Invention
This invention relates to an ice stock level detecting apparatus for ice making machines and more particularly to a holder assembly for holding the temperature sensor element of a thermostat of an ice stock level detecting apparatus.
2. Description of the Prior Art
In automatic ice making machines, ice pellets or pieces as produced are generally stored in an ice storage chamber (also referred to as a stocker). When the stored ice pieces (i.e. the ice stock level) has reached a predetermined amount, the ice making operation has to be automatically stopped. To this end, the ice making machine is provided with an apparatus for detecting the predetermined amount of the stocked ice pieces, which apparatus generally comprises a thermostat provided with a temperature sensor element adapted to be disposed within the ice storage chamber or stocker.
It has however been found that the thermostat is likely to erroneously operate so that the ice filled state within the stocker may possibly be detected notwithstanding of the fact that the ice pieces are not yet stored to the level corresponding to the position of the temperature sensor element, because it responds to the cold air cooled down by an ice making unit during the ice making operation cycle and by the radiation emanating from those ice pieces which are stored within the stocker. As an attempt for solving this problem, it has heretofore been known to mount the temperature sensor element at the tip of a small diameter tube wound with a heating wire so that the thermostat responds to the lowering in temperature brought about by the contact of the sensor element with the ice piece to thereby detect the predetermined ice stock level. In order to detect with high accuracy the temperature drop caused by the contact with the ice piece, the temperature sensor element should preferably be implemented with a low thermal capacity or a reduced surface area. For this reason, the temperature sensor element was formed in a very thin or fine elongated structure.
Also, the above temperature sensor element is held so as to project from an inner wall surface of the stocker in order that the sensor element can readily contact the ice piece. More specifically, as shown in FIG. 6, a holder A having a projection B of inverted L-like cross-section is fixedly mounted on an inner wall surface C of a stocker by means of screws D or the like, and a temperature sensor element F is mounted on a vertically disposed tongue plate E of the projection B by clamps G. A small diameter tube H extending from the temperature sensor element F is wound with a heating wire I and led out to a controller of the ice making machine (not shown).
As the temperature sensor element F of the above-discussed ice stock level detecting apparatus is very thin and simply supported between a pair of bifurcated suspending arms extending downwardly from the vertical tongue plate E, it is very susceptible to deformation and injury under the influence of external forces possibly applied to the element when the ice pieces are taken out, resulting in the intolerable degradation or lost of the ice detection capability of the ice stock level detecting apparatus. For example, when ice pieces J stored within the stocker are to be taken out, a scoop of a small size having a short half or grip (not shown) is usually employed. In this case, upon taking out the ice pieces, the scoop is put into a heap K of ice pieces J, moved horizontally and then swung upwardly around a root of the grip to thereby scoop up the ice pieces. In this connection, it is noted that so far as the ice stock level detecting apparatus operates normally, the ice stock level within the stocker will remain short of the height of the termperature sensor element F. Accordingly, when the ice pieces are scooped up, an external force of the upward direction is likely to be transmitted to the temperature sensor element F as will be understood from FIG. 6. As a result, the termperature sensor element F is deformed or damaged as mentioned above.
As an approach to protect the temperature sensor element against the deformation, it has also been proposed to enclose the sensor element with a perforated protection tube (refer to Japanese Laid-Open Utility Model Publication No. 141679/1986). However, this structure also suffers from a problem that because the temperature sensor element is housed within the perforated protection tube, the sensor element is not easy to contact with the ice pieces nevertheless of the presence of apertures in the protection tube and that any ice piece once brought into contact with the temperature sensor element through the aperture continues to stay in that contact position until it has been defrozened. Thus, the known sensor element is difficult to reliably detect a decrease in the ice stock level.